/**
 * @file sync.cpp
 * @author your name (you@domain.com)
 * @brief 特殊语法学习
 * @version 0.1
 * @date 2022-03-24
 * 
 * @copyright Copyright (c) 2022
 * HandlePool(const HandlePool &) = delete;和 = default;
 * https://blog.csdn.net/weixin_42226134/article/details/104797124
 * 
 */